A specilization of shaped thing and solid object. Each instance of panel is an object that is flat and spread out, planar, and neither fully crumpled nor compactly folded. Such an object has two opposing surfaces that are both FlatSurfaceRegions (q.v.); its other surfaces have much smaller area than the two main flat surfaces. Thus, one of the three orthogonal dimensions (length, width or height) of a sheet-shaped object is much smaller than the other two.

Examples of panel include a layer of ice over a pond and a piece of plywood. A bedspread is a sheet-shaped object only if it is not folded into a small volume or crumpled. (See Current Shape Vs Intrinsic Shape.)

For describing a sheet of something (e.g. waxed paper, aluminum foil, cloth) regardless of its current shape, use sheet of some substance. For one-sided surfaces, use a specialization of surface.